Electronic memory cards are now well known. Such a card is essentially constituted by a generally rectangular card body having an electronic module implanted therein. The electronics comprises an integrated circuit including at least one memory circuit, together with external electrical contact tabs which are connected to the terminals of the integrated circuit. In order to use such a card, it is inserted into a card-processing machine. The card-processing machine includes processing circuits for making use of information contained in the card memory and for modifying said information, together with a read/write device which provides a temporary electrical connection between the contact tabs on the card and the processing circuits in the machine. This connection serves to supply electrical power to the integrated circuit in the card, to transmit read/write instructions to the card memory, to apply the write voltage and a clock signal, etc.
A read/write device usually comprises a housing having a slot in its front face through which the card is inserted, and which defines an internal guide passage for positioning the card in such a manner that when it is in a processing position, i.e. when it is fully inserted, the contact tabs of the card come into electrical contact with a connector which is mounted in the guide passage. For memory cards in compliance with the ISO standard, the contact tabs are disposed close to a corner of the card body. The connector of the read/write device is thus off-center from the mid-plane of the read/write device.
Several types of read/write device exist. In some of them, when the card is in the processing position, it is only partially inserted into the guide passage, thereby enabling the card to be moved either manually by the user or else by a wheel driven by a motor. The device is then referred to as a "non-swallowing" device. In other read/write devices the card is fully inserted into the guide passage prior to arriving in the processing position, and card displacement in both directions is obtained by a drive motor. With this second type of device, referred to as a "swallowing" device, it is certain that the card user will not move the card while it is being processed. However, if the card displacement means become faulty, the card may remain jammed in the guide passage which is inconvenient for the card owner and damaging for the organization running the read/write device since the device becomes unusable until it has been repaired.
In addition, many users are reticent about having their cards completely swallowed by the read device.
With the first type of read/write device, the risk and fear of the card becoming jammed inside the device do not exist since a portion of the card body always projects from the card reader. However, both types of read/write device may suffer from acts of vandalism seeking to prevent them from operating. One of the most frequent acts of vandalism consists in inserting a fragment only of an authentic card body in the guide passage of the read/write device, said fragment being cut so that its length is slightly less than the length of the guide passage for use with a reader of the first type, and slightly less than the stroke of card displacement for use with a reader of the second type. In either case, users arriving after the act of vandalism has been performed cannot use the read/write device since the card body fragment therein cannot be extracted from the guide passage. This requires a maintenance team to be called and prevents the read/write device from operating for a non-negligible period of time.
Another form of vandalism consists in spoiling the electrical contacts of the read/write head of the device. This can easily be done by inserting a metal blade or similar object into the card insertion slot instead of a card, and then using the blade to break or deform the electrical contacts. As a general rule these contacts project into the guide passage.
An object of the invention is to provide a read/write device for electronic memory cards which serves to prevent these acts of vandalism, or at least to make them more difficult.